Parking control system for vehicle

ABSTRACT

In a vehicle parking control system, to apply sufficient braking force quickly and reliably to a parking brake when a shift range of an automatic transmission changes to a Park range, thereby reliably preventing an operator from forgetting to engage the parking brake. 
     A vehicle parking control system includes a range-switching device  26  that operates in conjunction with a shift lever  61,  which is operated by an operator, and that switches a shift range of an automatic transmission  20  and switches a parking mechanism  27  that is provided in the automatic transmission  20  to an engaged state and a released state; an electric parking brake unit  50  that is operated based on a range position signal, which corresponds to the shift range of the automatic transmission  20,  and that switches a parking brake  53  of the vehicle to a braking state and a released state; and an automatic transmission ECU  60  that operates the electric parking brake unit  50  based on the range position signal of the vehicle.

DETAILED DESCRIPTION OF THE INVENTION

1. Technical Field

The present invention relates to a vehicle parking control system.

2. Related Art

A parking brake is well known as a conventional method of holding avehicle in a stopped state when it is parked. The parking brake isgenerally structured from a parking brake main body that is provided ona wheel and a lever member (or a pedal member) that is connected by acable and is operated by an occupant of the vehicle.

Also, in a vehicle equipped with an automatic transmission, a parkingmechanism that is provided in the automatic transmission is also wellknown as a method of holding the vehicle in a stopped state. The parkingmechanism functions such that when the shift lever is moved into thePark range (P range), a parking pawl that is connected to the shiftlever disengageably engages a parking gear that is fixed to an outputshaft of the automatic transmission, thereby stopping the rotation ofthe output shaft and stopping the rotation of a driving wheel that isconnected to the output shaft.

Therefore, when parking, the occupant must execute separately the abovetwo methods of holding the vehicle in a stopped state. That is, theoccupant must move the shift lever into the Park range (P range) to putthe parking mechanism into an engaged state and also pull the hand brakethat is the lever member to put the parking brake into a braking state.

Accordingly, as shown in Patent Document 1, a vehicle shift apparatushas been proposed in which the automatic transmission shift lever andthe parking brake lever member operate in conjunction. That is, thevehicle shift apparatus mechanically couples the shift lever and theparking brake. Specifically, the vehicle shift apparatus 1 is structuredsuch that the shift lever 2 is connected to a brake cable 10, and whenthe shift lever 2 moves to the Park range position from the Reverserange position, which is adjacent to the Park range position, the brakecable 10 becomes taut and the parking brake operates.

[Patent Document 1] Japanese Patent Application Publication No.JP-A-2004-243927

[Problem to be Solved by the Invention]

In the vehicle shift apparatus described in Patent Document 1, theparking mechanism can be put into the engaged state and the parkingbrake can be put into the braking state by the single operation ofmoving the shift lever into the Park range position, which prevents theoccupant from forgetting to apply the parking brake. However, becausethe shift lever and the parking brake lever member operate inconjunction, the parking brake cannot exert sufficient braking forceuntil the shift lever arrives at the Park range position. There is alsoconcern that if the tension in the parking brake cable decreases due tothe cable's stretching or the like, the parking brake might not exertsufficient braking force even when the shift lever is positioned at thePark range position.

It is an object of the present invention to provide a vehicle parkingcontrol system that solves the problems described above by quickly andreliably providing sufficient braking force to the parking brake whenthe shift range of the automatic transmission changes, while alsoreliably preventing the occupant from forgetting to apply the parkingbrake.

[Means for Solving the Problem]

In order to solve the problems described above, the structuralcharacteristics of the present invention according to claim 1 includerange selection means that is operated by an operator and that selects ashift range of a drive unit for a desired range; a range-switchingdevice that operates in conjunction with the range selection means andthat switches a parking mechanism that is provided in the drive unit toan engaged state and a released state; a parking unit that is operatedbased on an electric range position signal, which corresponds to theshift range, and that switches a brake unit that is provided in thevehicle to a braking state and a released state; and a control unit thatoperates the parking unit based on the range position signal of vehicle.

The structural characteristics of the present invention according toclaim 2 include range selection means that is operated by an operatorand that selects a shift range of an automatic transmission for adesired range; a range-switching device that operates in conjunctionwith the range selection means and that switches a parking mechanismthat is provided in the automatic transmission to an engaged state and areleased state; a parking unit that is operated based on an electricrange position signal, which corresponds to the shift range, and thatswitches a brake unit that is provided in the vehicle to a braking stateand a released state; and a control unit that operates the parking unitbased on the range position signal of vehicle.

The structural characteristics of the present invention according toclaim 3 include the structural characteristics according to claim 1 or2, in which the shift range includes a Park range, a Reverse range, aNeutral range, and a Drive range; and the control unit operates theparking unit when the range position signal is one of a signal to switchthe shift range to the Park range and a signal to switch the shift rangeout of the Park range.

The structural characteristics of the present invention according toclaim 4 include the structural characteristics according to any one ofclaims 1 to 3, in which the range position signal is a range commandsignal.

The structural characteristics of the present invention according toclaim 5 include the structural characteristics according to any one ofclaims 1 to 3, in which the range position signal is a range statesignal.

The structural characteristics of the present invention according toclaim 6 include the structural characteristics according to claim 4, inwhich the range selection means has a function that detects the selectedrange and outputs a range signal, which is a detection signal, to thecontrol unit; and the range command signal is the range signal.

The structural characteristics of the present invention according toclaim 7 include the structural characteristics according to claim 5, inwhich the range state signal is a signal that is output to the controlunit from range state detection means that detects the shift rangestate.

The structural characteristics of the present invention according toclaim 8 include the structural characteristics according to any one ofclaims 1 to 3, in which when the range position signal is the signal toswitch the shift range to the Park range, the control unit operates theparking unit to switch the brake unit to the braking state.

The structural characteristics of the present invention according toclaim 9 include the structural characteristics according to any one ofclaims 1 to 3, in which when the range position signal is the signal toswitch the shift range out of the Park range, the control unit operatesthe parking unit to switch the brake unit to the released state.

The structural characteristics of the present invention according toclaim 10 include the structural characteristics according to any one ofclaims 1 to 3, in which the range position signal is made up of a rangecommand signal and a range state signal, and the parking unit isoperated according to one of the range command signal and the rangestate signal.

The structural characteristics of the present invention according toclaim 11 include the structural characteristics according to any one ofclaims 1 to 3, in which the range position signal is made up of a rangecommand signal and a range state signal; the parking unit sets the brakeunit to the braking state, according to one of the range command signaland the range state signal; and the parking unit sets the brake unit tothe released state, according to the other of the range command signaland the range state signal.

The structural characteristics of the present invention according toclaim 12 include the structural characteristics according to claim 8, inwhich the brake unit is set to the braking state before the parkingmechanism is set to the engaged state.

The structural characteristics of the present invention according toclaim 13 include the structural characteristics according to claim 9, inwhich the brake unit is set to the released state at or after the timewhen the parking mechanism is set to the released state.

The structural characteristics of the present invention according toclaim 14 include the structural characteristics according to claim 8, inwhich the parking unit is structured from at least one of a parkingbrake unit that operates a parking brake and a wheel brake unit thatoperates a wheel brake; and one of the parking brake unit and the wheelbrake unit is set to the braking state before the parking mechanism isset to the engaged state.

The structural characteristics of the present invention according toclaim 15 include the structural characteristics according to claim 9, inwhich the parking unit is structured from at least one of a parkingbrake unit that operates a parking brake and a wheel brake unit thatoperates a wheel brake; and one of the parking brake unit and the wheelbrake unit is set to the released state at or after the time when theparking mechanism is set to the released state.

EFFECTS OF THE INVENTION

In the present invention according to claim 1 structured as describedabove, in a case where the operator moves the shift lever to the Parkrange position, when the control unit detects that the range positionsignal has changed to the Park range, the control unit the parking unitbased on the range position signal that indicates the Park range. Thus,the parking mechanism can be set to the engaged state, and the parkingbrake can apply sufficient braking force, quickly and reliably, therebyreliably preventing the operator from forgetting to engage the parkingbrake.

Also, in a case where the operator moves the shift lever out of the Parkrange position, when the control unit detects that the range positionsignal has changed from the Park range, the control unit operates theparking unit based on the range position signal that indicates a rangeother than the Park range. Thus, the parking mechanism can be set to thereleased state, and the parking brake can release, quickly and reliably,thereby reliably preventing the operator from forgetting to release theparking brake.

In the present invention according claim 2 structured as describedabove, in a case where the operator moves the shift lever to the Parkrange position, when the control unit detects that the range positionsignal has changed to the Park range, the control unit operates theparking unit based on the range position signal that indicates the Parkrange. Thus, the parking mechanism can be set to the engaged state, andthe parking brake can apply sufficient braking force, quickly andreliably, thereby reliably preventing the operator from forgetting toengage the parking brake.

Also, in a case where the operator moves the shift lever out of the Parkrange position, when the control unit detects that the range positionsignal has changed from the Park range, the control unit operates theparking unit based on the range position signal that indicates a rangeother than the Park range. Thus, the parking mechanism can be set to thereleased state, and the parking brake can release, quickly and reliably,thereby reliably preventing the operator from forgetting to release theparking brake.

In the present invention according to claim 3 structured as describedabove, in the present invention according to claim 1 or claim 2, theshift range includes a Park range, a Reverse range, a Neutral range, anda Drive range, and the control unit operates the parking unit when therange position signal is one of a signal to switch the shift range tothe Park range and a signal to switch the shift range out of the Parkrange. Therefore, the control unit operates the parking unit reliablyand correctly according to the shift range.

In the present invention according to claim 4 structured as describedabove, in the present invention according to any one of claim 1 to claim3, the range position signal is the range command signal. Therefore, theparking unit operates reliably and correctly according to the shiftlever operation.

In the present invention according claim 5 structured as describedabove, in the present invention according to any one of claim 1 to claim3, the range position signal is the range state signal. Therefore, theparking unit operates reliably and correctly according to an actualrange state of the automatic transmission (the drive unit).

In the present invention according to claim 6 structured as describedabove, in the present invention according to claim 4, the range commandsignal is the range signal, which is a detection signal of the rangeselected by the range selection means. Therefore, the parking unitoperates with good responsiveness to the operation of the shift lever.

In the present invention according to claim 7 structured as describedabove, in the present invention according to claim 5, the range statesignal is a signal that is output to the control unit from the rangestate detection means that detects the shift range state. Therefore, theparking unit operates reliably and correctly according to the actualrange state.

In the present invention according to claim 8 structured as describedabove, in the present invention according to any one of claim 1 to claim3, when the range position signal is the signal to switch the shiftrange to the Park range, the control unit operates the parking unit toswitch the brake unit to the braking state. Therefore, the operator isreliably prevented from forgetting to engage the parking brake.

In the present invention according to claim 9 structured as describedabove, in the present invention according to any one of claim 1 to claim3, when the range position signal is the signal to switch the shiftrange out of the Park range, the control unit operates the parking unitto switch the brake unit to the released state. Therefore, the operatoris reliably prevented from forgetting to release the parking brake.

In the present invention according claim 10 structured as describedabove, in the present invention according to any one of claim 1 to claim3, the range position signal is made up of a range command signal and arange state signal, and the parking unit is operated according to one ofthe range command signal and the range state signal. Therefore, theparking unit can be operated reliably.

In the present invention according to claim 11 structured as describedabove, in the present invention according to any one of claim 1 to claim3, the range position signal is made up of a range command signal and arange state signal; the parking unit sets the brake unit to the brakingstate, according to one of the range command signal and the range statesignal; and the parking unit sets the brake unit to the released state,according to the other of the range command signal and the range statesignal. Therefore, the brake unit can be engaged and released reliably.

In the present invention according claim 12 structured as describedabove, in the present invention according to claim 8, the brake unit isset to the braking state before the parking mechanism is set to theengaged state. Thus, when the operator parks the vehicle, the parkingmechanism is set to the engaged state based on a circumstance in whichthe vehicle is in a parked state, with the wheels held stationary andthe like, and there is no movement in the output shaft of the automatictransmission (the drive unit). Therefore, the generation of loud noiseand shock resulting from the engagement of the parking mechanism whilethe output shaft is rotating can reliably be prevented.

In the present invention according to claim 13 structured as describedabove, in the present invention according to claim 9, the brake unit isset to the released state at or after the time when the parkingmechanism is set to the released state. Thus, when the operator releasesthe vehicle from the parked state, the parking mechanism is set to thereleased state based on a circumstance in which the vehicle is parked,with the wheels held stationary and the like, and there is no movementin the output shaft of the automatic transmission (the drive unit).Therefore, the generation of loud noise and shock resulting from therelease of the parking mechanism while the output shaft is rotating canreliably be prevented.

In the present invention according claim 14 structured as describedabove, in the present invention according to claim 8, the parking unitis structured from at least one of a parking brake unit that operates aparking brake and a wheel brake unit that operates a wheel brake, andone of the parking brake unit and the wheel brake unit is set to thebraking state before the parking mechanism is set to the engaged state.Thus, when the operator parks the vehicle, it is possible to engage theparking brake after the wheel brake is engaged and to set the parkingmechanism to the engaged state after the output shaft of the automatictransmission (drive unit) stops moving, while ensuring a high degree offreedom in design.

In the present invention according to claim 15 structured as describedabove, in the present invention according to claim 9, the parking unitis structured from at least one of a parking brake unit that operates aparking brake and a wheel brake unit that operates a wheel brake, andone of the parking brake unit and the wheel brake unit is set to thereleased state at or after the time when the parking mechanism is set tothe released state. Thus, when the operator releases the vehicle fromthe parked state, it is possible to release the wheel brake after theparking brake is released and to release the vehicle from the parkedstate after the parking mechanism is set to the released state, whileensuring a high degree of freedom in design.

Embodiment(s) of the Invention

An embodiment of a vehicle parking control system according to thepresent invention will be explained below with reference to thedrawings. FIG. 1 is a schematic diagram that shows the structure of thevehicle. FIG. 2 is a schematic diagram that shows the structure of anautomatic transmission. FIG. 3 is an oblique view that shows a parkingmechanism. FIG. 4 is a schematic diagram that shows the structure of anautomatic transmission ECU shown in FIG. 1.

The vehicle M is a rear-wheel drive vehicle equipped with an automatictransmission 20, which is a drive unit. The vehicle M is of a type inwhich a driving force of an engine 11, which is a prime mover mounted ina front portion of the vehicle body, is transmitted through theautomatic transmission 20 to a rear wheel, which is a driving wheel.Note that the vehicle M may also be a front-wheel drive vehicle or afour-wheel drive vehicle, for example, instead of a rear-wheel drivevehicle.

The vehicle M is equipped with the vehicle parking control system. Thevehicle parking control system is equipped with a range-switching device26, which is provided in the automatic transmission 20, an electricparking brake unit (hereinafter called an electric PKB unit) 50, whichis a parking unit, and the automatic transmission electronic controlunit (ECU) 60.

The automatic transmission 20 shifts the speed of the driving force ofthe engine 11 and transmits it through a propeller shaft 13, adifferential 14, and left and right drive shafts 15 a, 15 b respectivelyto the left and right rear wheels Wrl, Wrr, which are the drivingwheels. As shown in FIG. 2, the automatic transmission 20 is providedwith a casing 21. An input shaft 22, a speed change mechanism 23, anoutput shaft 24, a hydraulic control unit 25, the range-switching device26, and the parking mechanism 27 are disposed within the casing 21.

The input shaft 22 inputs the driving force from the engine 10. Thespeed change mechanism 23 includes a torque converter, a planetary geartrain, and the like. The speed change mechanism 23 receives commandsfrom the hydraulic control unit 25, shifts gear speeds (shifting andinverse rotation) to shift the speed of the driving force input by theinput shaft 22, and outputs the driving force. The output shaft 24,through the propeller shaft 13, outputs to the driving wheels (Wrl, Wrr)the driving force that was shifted by the speed change mechanism 23.

The hydraulic control unit 25 controls the planetary gear train byautomatically switching the oil passages for the brakes and the clutchesfor various gears in the planetary gear train. As shown in FIG. 2, thehydraulic control unit 25 is provided with a manual valve 25 a, which isdriven by the range-switching device 26. The manual valve 25 a switchesline pressure oil passages to match a range selected by a shift lever61, thereby switching the operating state of the automatic transmission20 to various shift ranges, such as the P range (Park range), R range(Reverse range), N range (Neutral range), D range (Drive range), and thelike. Selectable ranges are set for the shift lever 61 that correspondto the various shift ranges of the automatic transmission 20. Also, themanual valve 25 a, which is disposed within the hydraulic control unit25 of the automatic transmission 20, can be moved to a P position thatcorresponds to the P range, an R position that corresponds to the Rrange, an N position that corresponds to the N range, a D position thatcorresponds to the D range, and the like. Moving the manual valve 25 ain the axial direction switches oil passages within the hydrauliccontrol unit 25 such that the shift range of the automatic transmission20 is set to the range selected by the shift lever 61, that is, therequested range.

As shown in FIGS. 1 and 2, the range-switching device 26 is linked tothe shift lever 61 (described later), which is range selection meansthat selects a shift range of the automatic transmission 20 for adesired shift range. The range-switching device 26 switches the shiftrange of the automatic transmission 20 and switches the parkingmechanism 27, which is provided in the automatic transmission 20, to anengaged state and a released state.

The range-switching device 26 is structured such that it includes amanual shaft 32, which is supported by the casing 21 of the automatictransmission 20 such that the manual shaft 32 rotates freely; a detentlever 31, an end portion of which is fastened to the manual shaft 32 toform a single piece with the manual shaft 32, such that the detent lever31 rotates together with the manual shaft 32; an outer lever 33, whichis fastened to a protruding end of the manual shaft 32 to form a singlepiece with the manual shaft 32, such that the outer lever 33 rotatestogether with the manual shaft 32; and a shift linkage 34, which linksthe outer lever 33 to the shift lever 61.

A parking rod 43 is connected to the other end portion of the detentlever 31, and the manual valve 25 a is also connected to the other endportion of the detent lever 31 through a connecting member 37. Thus,when the detent lever 31 rotates in the directions indicated by arrowG-H in FIG. 2, the parking rod 43 and the manual valve 25 a move in theaxial direction (the direction indicated by arrow E-F in FIG. 1).

Around an edge of the other end portion of the detent lever 31, aplurality of range grooves are formed that are disengageably engaged bya roller 36, which is supported by a tip of a detent spring (omittedfrom the drawings), such that the roller 36 rotates freely. The rangegrooves correspond to the P position, the R position, the N position,and the D position of the manual valve 25 a. For example, in FIG. 2, therange groove on the right end corresponds to the D range, and the rangegroove on the left end corresponds to the P range. FIG. 2 shows a statein which the roller 36 is engaged with the range groove on the rightend, that is, a state in which the automatic transmission 20 is in the Drange. Also, FIG. 1 shows the shift lever 61 in a state of being in theD range.

In the range-switching device 26 structured in this manner, when theshift lever 61 is operated in the direction indicated by arrow E, theshift linkage 34 is moved in the direction indicated by arrow F, and theouter lever 33 is swung (rotated) in the direction indicated by arrow G.In conjunction with this movement, the detent lever 31 swings in thedirection indicated by arrow G, causing the parking rod 23 and themanual valve 25 a to be moved in the direction indicated by arrow F.Also when the shift lever 61 is moved in the direction indicated byarrow F, the shift linkage 34 is moved in the direction indicated byarrow E, and the outer lever 33 is swung (rotated) in the directionindicated by arrow H. In conjunction with this movement, the detentlever 31 swings in the direction indicated by arrow H, causing theparking rod 23 and the manual valve 25 a to be moved in the directionindicated by arrow E.

Note that it is desirable for the range-switching device 26 to bestructured such that, when the shift lever 61 is changed from the Rrange to the P range, the parking mechanism 27 changes from the releasedstate to the engaged state at or before the time that parking brakes 53change from a released state to a braking state. It is also desirablefor the range-switching device 26 to be structured such that, when achange is made from the P range to the R range, the parking brakes 53change from the braking state to the released state at or after the timewhen the parking mechanism 27 changes from the engaged state to thereleased state. For example, a device may be interposed in the shiftlinkage 34 such that when the shift lever 61 is changed from the R rangeto the P range, the device contracts in the axial direction, therebydelaying the transmission of the force of the shift lever 61 to theouter lever 33, and when the shift lever 61 is changed from the P rangeto the R range, the device extends in the axial direction, therebyspeeding up the transmission of the force of the shift lever 61 to theouter lever 33.

The automatic transmission 20, as shown in FIG. 1, is equipped with aneutral start switch (hereinafter called the N switch) 35. The N switch35 is attached to the casing 21 of the automatic transmission 20 and isrange state detection means that detects the shift range state, which isthe operating state of the automatic transmission 20, through a contactpoint that moves in conjunction with the shift lever 61, that is, themanual shift 32. A contact point pattern signal (or a converted patternsignal in which the contact point pattern signal is converted to acorresponding range), which is a detection result (detection signal)detected by the N switch 35, is output to the automatic transmission ECU60.

The parking mechanism 27, as shown in FIG. 3, is mainly structured froma parking gear 41, a parking pawl 42, the parking rod 43, and a cam 44.The parking mechanism 27 executes parking locking by stopping therotation of the output shaft 24. The parking mechanism 27 stops therotation of the output shaft 24 by causing a tooth 42 a of the parkingpawl 42 to engage with the parking gear 41, which is provided as anintegral part of the output shaft 24.

As the output shaft 24 rotates, the parking gear 41 rotates as indicatedby arrow A-B in FIG. 3. The parking pawl 42 is disposed such that itrotates freely in the directions indicated by arrow C-D in FIG. 3 arounda support point 42 b, which is fastened to the casing 21. The parkingpawl 42 is energized in the arrow D direction by a spring not shown inFIG. 3.

The parking rod 43 is disposed such that it extends parallel to theoutput shaft 24. A base end portion 43 a of the parking rod 43 isconnected to the detent lever 31 such that the parking rod 43 movesreciprocally in the axial direction (the direction indicated by arrowE-F in FIG. 3) in conjunction with the rotation of the detent lever 31.The conical cam 44 is provided at a tip portion 43 b of the parking rod43. The cam 44 moves back and forth between the parking pawl 42 and asupport member 45 according to the reciprocal movement of the parkingrod 43, thereby causing the parking pawl 42 to rock. The cam 44 isfitted onto the parking rod 43 such that the cam 44 slides freely on theparking rod 43 and is energized toward the tip of the parking rod 43(the F direction) by a spring 43 c.

In a case where the detent lever 31 is rotated, the parking rod 43 ismoved toward the rear of the vehicle (the F direction), and the cam 44is also moved toward the rear of the vehicle, when the position of agear space on the parking gear 41 is aligned with the position of thetooth 42 a on the parking pawl 42, the cam 44 moves into the spacebetween the parking pawl 42 and the support member 45. This causes theparking pawl 42 to be rocked in the direction indicated by arrow C, inopposition to the energizing force of the spring not shown in FIG. 3,such that the parking pawl 42 is disposed in a position to engage theparking gear 41. Therefore, the tooth 42 a enters a state of engagementwith the gear space of the parking gear 41 such that the output shaft 24and, as a consequence, the drive shaft are held stationary.

When the position of the gear space on the parking gear 41 is notaligned with the position of the tooth 42 a on the parking pawl 42, thetooth 42 a enters a state of contact with the top land of a gear toothon the parking gear 41, and a gap large enough for the cam 44 to movebetween the parking pawl 42 and the support member 45 is not formed.Therefore, even though the parking rod 43 is moved into the parkingposition, the movement of the cam 44 is restricted by the parking pawl42 and the support member 45. At this time, the cam 44 is energizedtoward the rear of the vehicle (the arrow F direction) by the spring 43c. This causes the parking pawl 42 to be energized in the directionindicated by arrow C and to enter a parking waiting state, as it were,in which the tooth 42 a presses against the parking gear 41. Thereafter,if the output shaft 24 rotates only slightly, such that the position ofthe gear space on the parking gear 41 is aligned with the position ofthe tooth 42 a on the parking pawl 42, the cam 44 is moved by theenergizing force of the spring 43 c in the direction indicated by arrowF and moves into the space between the parking pawl 42 and the supportmember 45. This causes the parking pawl 42 to be rocked in the directionindicated by arrow C, in opposition to the energizing force of thespring not shown in FIG. 3, such that the parking pawl 42 is disposed inan engaged position and the parking mechanism 27 enters a state ofengagement (parked state).

By contrast, in a case where the detent lever 31 is rotated, the parkingrod 43 is moved toward the front of the vehicle (the E direction) fromthe parking position, and the cam 44 is also moved toward the rear ofthe vehicle, the cam 44 comes out from between the parking pawl 42 andthe support member 45. The energizing force of the spring not shown inFIG. 3 in the arrow D direction therefore rocks the parking pawl 42 in adirection that separates it from the parking gear 41 (the arrow Ddirection). At the same time, the state of engagement between the tooth42 a and the gear space of the parking gear 41 is released (that is,enters a released state), such that the output shaft 24 and, as aconsequence, the drive shaft are allowed to rotate.

Therefore, the shift-switching device 26 switches the shift range of theautomatic transmission 20 in conjunction with the operation of the shiftlever 61 and also operates the parking mechanism 27 that is provided inthe automatic transmission 20.

The electric PKB unit 50, which is the parking unit, is operatedautomatically based on a range position signal and switches the parkingbrakes 53, which are brake units that are provided in the vehicle M, tothe braking state and the released state. That is, the electric parkingbrake unit 50, which is the parking unit, is operated automaticallybased on the range position signal and operates the parking brakes 53,which are brake units that are provided in the vehicle M. The electricparking brake unit 50 also switches the vehicle M to a parked state anda released state by operating the vehicle's parking brakes 53.

The electric PKB unit 50 is structured from a parking brake actuatorportion 51 (hereinafter called a PKB actuator portion), a wire structureportion 52, a pair of left and right parking brakes 53L, 53R, which areprovided on the left and right rear wheels Wrl, Wrr, a tensile forcesensor 54, and the like.

The PKB actuator portion 51 is structured from a motor 51 a, whichserves as an electric driving means and can rotate both forwards and inreverse, and a deceleration mechanism 51 b, which serves as a powertransmission and cut-off mechanism and is made up of a plurality of geartrains that are structured such that the driving force of the motor 51 acan be transmitted to the wire structure portion 52, while power basedon tensile force from the wire structure portion 52 is not transmittedto the motor 51 a. The motor 51 a is controlled based on the rangeposition signal, which is a command signal from the automatictransmission ECU 60.

The wire structure portion 52 is structured from a base wire 52 a, anend of which is connected to the deceleration mechanism 51 b; a balancer52 b, a center portion of a side of which is connected to an other endof the base wire 52 a; and a left wire 52 cL and a right wire 52 cR,each of which has an end that is connected to an edge of an other sideof the balancer 52 b and which have other ends that are respectivelyconnected to the left-right pair of parking brakes 53L, 53R.

The balancer 52 b inclines as necessary in the direction of vehicle yawsuch that the tensile force on the left wire 52 cL and the tensile forceon the right wire 52 cR are always of the same magnitude, even if thereis initial dimensional variation in the length of the left wire 52 cLand the length of the right wire 52 cR or if differences arise due toaging changes or the like.

The left-right pair of parking brakes 53L, 53R are one-piece typeparking brakes in which operating mechanisms are respectivelyincorporated into wheel brakes WBrl, WBrr. The parking brakes 53L, 53Rare structured such that they respectively generate braking force on theleft and right rear wheels Wrl, Wrr according to the tensile force ofthe left wire 52 cL and the right wire 52 cR (that is, according to thetensile force of the base wire 52 a). Therefore, the action of thebalancer 52 b causes equal braking forces to be generated in theleft-right pair of parking brakes 53L, 53R.

The tensile force sensor 54 is provided on the base wire 52 a. Thetensile force sensor 54 detects the tensile force on the base wire 52 aand outputs a signal to the automatic transmission ECU 60 that indicatesa tensile force Fw on the base wire 52 a.

The automatic transmission ECU 60 is a control unit that operates thehydraulic control unit 25, and that also operates the electric PKB unit50 based on the relationship between the range position signal and thePark range of the vehicle M. As described above, the N switch 35, themotor 51 a and the tensile force sensor 54 of the electric PKB unit 50,and the hydraulic control unit 25 are connected to the automatictransmission ECU 60. Also, as mainly shown in FIG. 4, a selector switch61 a of the shift lever 61, an outside air temperature sensor 62, and avehicle speed sensor 28 of the automatic transmission 20 are connectedto the automatic transmission ECU 60. An engine electronic control unit(ECU) 16, and a brake electronic control unit (ECU) 76 are alsoconnected to the automatic transmission ECU 60 such that they cancommunicate with one another.

The automatic transmission ECU 60 has a microcomputer (omitted from thedrawings), and the microcomputer is equipped with input/outputinterfaces, which are connected through a bus, a CPU, a RAM, and a ROM(all omitted from the drawings). The CPU executes programs thatcorrespond to the flowcharts in FIGS. 6 to 12 and controls theengage/release switching of the parking brakes 53L, 53R. The RAMtemporarily stores variables that are required for the execution of theprograms. The ROM stores the programs.

The selector switch 61 a is provided on the shift lever 61 and is rangedetection means that detects the selected range and outputs a rangesignal, which is a range detection signal, to the automatic transmissionECU 60. The selector switch 61 a forms a portion of the range selectionmeans.

The outside air temperature sensor 62 detects the air temperatureoutside the vehicle M and outputs an outside air temperature detectionsignal to the automatic transmission ECU 60. The vehicle speed sensor 28is provided in the automatic transmission 20. The vehicle speed sensor28 detects the revolution speed of the output shaft 24, which correlatesto the vehicle speed, and outputs the revolution speed to the automatictransmission ECU 60. The engine ECU 16 controls the engine 11. Theengine ECU 16 inputs the revolution speed of the engine 11 and outputsit to the automatic transmission ECU 60.

The vehicle parking brake control system is also equipped with ahydraulic brake unit (wheel brake unit) 70, which brakes the vehicle bydirectly applying hydraulic braking force to wheels Wfl, Wfr, Wrl, Wrr.The hydraulic brake unit 70 is structured from a brake pedal 71, avacuum booster 72, a master cylinder 73, a reservoir tank 74, a brakeactuator 75, the brake ECU 76, wheel brakes WBfl, WBfr, WBrl, WBrr, andwheel speed sensors Sfl, Sfr, Srl, Srr, which respectively detect thewheel speeds of the wheels Wfl, Wfr, Wrl, Wrr.

Each of the wheel brakes WBfl, WBfr, WBrl, WBrr contains a piston(omitted from the drawings), which slides in a liquid-tight manner. Whena base hydraulic pressure or a control hydraulic pressure is supplied toeach of the wheel brakes WBfl, WBfr, WBrl, WBrr, each piston presses ona pair of brake pads. The pairs of brake pads then press from both sideson disc rotors DRfl, DRfr, DRrl, DRrr, which rotate as single units withthe wheels Wfl, Wfr, Wrl, Wrr, thereby restricting the rotation of thedisc rotors DRfl, DRfr, DRrl, DRrr. Note that disc brakes are used inthis embodiment, but drum brakes may also be used.

The vacuum booster 72 is a servo unit that multiplies (increases) thebrake operating force that is generated by the operation of depressingthe brake pedal 71. The master cylinder 73 supplies brake fluid (oil) tocylinders in which the pistons in the wheel brakes WBfl, WBfr, WBrl,WBrr slide, at a hydraulic pressure (oil pressure) that is the basehydraulic pressure that corresponds to the brake operating force that ismultiplied by the vacuum booster 72. The reservoir tank 74 stores thebrake fluid and supplies the brake fluid to the master cylinder 73.

The brake actuator 75 is provided between the master cylinder 73 and thewheel brakes WBfl, WBfr, WBrl, WBrr and creates a control hydraulicpressure that is independent of the base hydraulic pressure that isgenerated in response to brake operating state. The brake actuator 75also supplies the base hydraulic pressure by passing it on. The brakeactuator 75 is provided with a control valve (electromagnetic), ahydraulic pressure source (motor, accumulator), and a reservoir and canindependently apply the control hydraulic pressure and the basehydraulic pressure to the wheel brakes WBfl, WBfr, WBrl, WBrr. The brakeECU 76 controls the brake actuator 75.

In the hydraulic brake unit 70, the base hydraulic pressure is generatedin the master cylinder 73 in response to the brake operating state thatis created by the depressing of the brake pedal 71. Directly applyingthe generated base hydraulic pressure to each of the wheel brakes WBfl,WBfr, WBrl, WBrr causes a base hydraulic pressure braking force thatcorresponds to the base hydraulic pressure to be generated on each ofthe wheels Wfl, Wfr, Wrl, Wrr.

Also in the hydraulic brake unit 70, irrespective of the brake operatingstate that is created by the depressing of the brake pedal 71, thecontrol hydraulic pressure is created in the brake actuator 75 based onthe wheel speeds detected by each wheel speed sensor Sfl, Sfr, Srl, Srr.Independently applying the control hydraulic pressure to each of thewheel brakes WBfl, WBfr, WBrl, WBrr causes a control hydraulic pressurebraking force to be generated independently on each of the wheels Wfl,Wfr, Wrl, Wrr.

The wheel brakes WBfl, WBfr, WBrl, WBrr may also be used as the parkingbrakes, and the hydraulic brake unit 70 may be used as the parking unit.

As shown in FIG. 5, the automatic transmission ECU 60 inputs the rangesignal, which is a command signal to the automatic transmission ECU 60from the selector switch 61 a of the shift lever 61. The range signal isa range command signal. From the N switch 35, the automatic transmissionECU 60 inputs a state (actual range) signal (that is, the automatictransmission range) for the manual shaft 33 d, that is, the patternsignal (or the converted pattern signal). The pattern signal is a rangestate signal. The range command signal and the range state signal arethe range position signals.

Next, the operation of the vehicle parking control system will beexplained with reference to the flowcharts shown in FIGS. 6 to 12. Whenthe vehicle's ignition switch is turned to ON, power is supplied to theengine ECU 16, and an initialization processing program shown in FIG. 6is started.

The engine ECU 16 supplies accessory power (step 102). If a key ID of akey to the vehicle M is identical to a pre-set vehicle ID (YES at step104), the engine ECU 16 sets an ID flag to ON (step 106). If the key IDis not identical to the vehicle ID (NO at step 104), the engine ECU 16sets the ID flag to OFF (step 108). The engine ECU 16 transmits the setID flag to the automatic transmission ECU 60 (step 110). With that, theinitialization of the engine ECU 16 ends.

Also, when the vehicle's ignition switch is turned to ON, power issupplied to the automatic transmission ECU 60, and an initializationprocessing program shown in FIG. 7 is started. The automatictransmission ECU 60 receives the ID flag from the engine ECU 16 (step202). If the received ID flag is OFF (NO at step 204), the automatictransmission ECU 60 sets a shift permission flag to OFF (step 206). Theautomatic transmission ECU 60 then transmits the shift permission flagto the engine ECU 16 (step 208).

Also, if the received ID flag is ON (NO at step 204), the automatictransmission ECU 60 receives an engine revolution speed from the engineECU 16 (step 210), sets the shift permission flag to ON (step 212), andoptimizes a hydraulic pressure increase for shifting (step 214). Theautomatic transmission ECU 60 then transmits the shift permission flagto the engine ECU 16 (step 208). With that, the initialization of theautomatic transmission ECU 60 ends.

Every time a specified short time interval elapses, the automatictransmission ECU 60, for which the initialization processing has endedas described above, executes an actual range position change controlprocessing routine that is shown in FIG. 8. If the range signal is thePark range or the actual range signal is the Park range (YES at step322), the automatic transmission ECU 60 executes parking brakeengagement processing (step 324). If neither the range signal nor theactual range signal is the Park range (NO at step 322), the automatictransmission ECU 60 executes parking brake release processing (step326).

Parking brake engagement processing is executed according to a parkingbrake engagement processing routine that is shown in FIG. 9. If therange signal is the Park range (YES at step 352), then if the vehiclespeed of the vehicle M, as detected by the vehicle speed sensor 28, isnot greater than a specified speed (for example, 5 km/h) (YES at step354), and if the outside air temperature detected by the outside airtemperature sensor 62 is higher than a specified value (for example, 0°C.) (YES at step 356), the automatic transmission ECU 60 operates themotor 51 a of the electric PKB unit 50 to put the parking brakes 53 intothe braking state (step 358). The automatic transmission ECU 60 thenends the parking brake engagement processing routine.

Note that it is desirable for the electric PKB unit 50 to be operated toput the parking brakes 53 from the released state into the braking stateat a point when a specified time has elapsed since the point when YESwas determined at step 352. The specified time is set to a time that isnecessary and sufficient for the parking mechanism 27 to change from thereleased state to the engaged state after the shift lever 61 is changedto the P range.

Also, when the range signal is not the Park range (NO at step 352), theautomatic transmission ECU 60 ends the parking brake engagementprocessing routine without operating the motor 51 a of the electric PKBunit 50.

If the range signal is the Park range (YES at step 352), but the vehiclespeed of the vehicle M is greater than the specified speed (NO at step354) or the outside air temperature is not higher than the specifiedvalue (NO at step 356), the automatic transmission ECU 60 ends theparking brake engagement processing routine without operating the motor51 a of the electric PKB unit 50.

Parking brake release processing is executed according to a parkingbrake release processing routine that is shown in FIG. 10. If the rangesignal is not the Park range (YES at step 362), the automatictransmission ECU 60 operates the motor 51 a of the electric PKB unit 50to put the parking brakes 53 into the released state (step 364). Theautomatic transmission ECU 60 then ends the parking brake releaseprocessing routine.

Note that it is desirable for the electric PKB unit 50 to be operated toput the parking brakes 53 from the braking state into the released stateat a point when a specified time has elapsed since the point when YESwas determined at step 362. The specified time is set to a time that isnecessary and sufficient for the parking mechanism 27 to change from theengaged state to the released state after the shift lever 61 is changedout of the P range.

If the range signal is the Park range (NO at step 362), the automatictransmission ECU 60 ends the parking brake release processing routinewithout operating the motor 51 a of the electric PKB unit 50.

Next, after the automatic transmission ECU 60 ends the parking brakerelease processing routine, it ends the actual range position changecontrol routine.

The engine ECU 16 also executes a termination processing routine that isshown in FIG. 11. That is, while the automatic transmission ECU 60executes each of the routines described above, as long as the vehicleignition switch is not turned to OFF (NO at step 122), the engine ECU 16sets an ignition flag to ON (step 124) and transmits the ignition flagto the automatic transmission ECU 60 (step 128). When the vehicleignition switch is turned to OFF (YES at step 122), the engine ECU 16sets the ignition flag to OFF (step 126) and transmits the ignition flagto the automatic transmission ECU 60 (step 128).

The automatic transmission ECU 60 also executes a termination processingroutine that is shown in FIG. 12. That is, the automatic transmissionECU 60 receives the ignition flag from the engine ECU 16 (step 232). Ifthe received ignition flag is OFF and the actual range is the Park range(YES at step 234), the automatic transmission ECU 60 sets the shiftpermission flag to OFF (step 238) and ends the termination processing.If the received ignition flag is ON or the actual range is not the Parkrange (NO at step 234), the automatic transmission ECU 60 transmits arequest signal to the engine ECU 16 to switch to the Park range (step236), then ends the termination processing.

Next, an engagement operation of the vehicle parking control systemdescribed above will be explained with reference to a time chart that isshown in FIG. 13. When the vehicle M is parked, if the operator changesthe shift lever 61 from the R range to the P range at time t1, the rangesignal is the P range, the actual range is the R range, the vehiclespeed is 0 km/h, and the outside air temperature is higher than thespecified value (YES at steps 322, 352, 354, 356), so the automatictransmission ECU 60 operates the motor 51 a of the electric PKB unit 50to change the parking brakes 53 from the released state to the brakingstate (from OFF to ON) (step 358).

Also, the range-switching device 26 operates in conjunction with thechanging of the shift lever 61 from the R range to the P range, and thedetent lever 31 rotates to an angle (position) that corresponds to the Prange. This causes the parking mechanism 27 to change from the releasedstate to the engaged state (time t2). However, in this case, the parkingbrakes 53 change from the released state to the braking state soonerthan the parking mechanism 27 changes from the released state to theengaged state, so the parking mechanism 27 can be set to the engagedstate after the parking brakes 53 are set to the braking state.

Next, at time t3, the operator releases the brake pedal 71, so brakingby the wheel brakes is released.

Next, a release (engagement release) operation of the vehicle parkingcontrol system described above will be explained with reference to atime chart that is shown in FIG. 14. When the vehicle M is released fromthe parked state, if the operator depresses the brake pedal 71 at timet11, the wheel brakes are set to the braking state. If the operator thenchanges the shift lever 61 from the P range to the R range at time t13,the range-switching device 26 operates in conjunction with the change,and the detent lever 31 rotates to an angle (position) that correspondsto the R range. This causes the parking mechanism 27 to change from theengaged state to the released state (from ON to OFF) (time t12).

Next, because the range signal is the R range and the actual range isthe P range (YES at step 362), the automatic transmission ECU 60operates the motor 51 a of the electric PKB unit 50 to change theparking brakes 53 from the braking state to the released state (from ONto OFF) (step 364). This causes the parking brakes 53 to change from thebraking state to the released state after the parking mechanism 27changes from the engaged state to the released state.

Note that in the embodiment described above, the range signal is used asthe signal for the processing at step 352 in FIG. 9 and for theprocessing at step 362 in FIG. 10, but the converted pattern signaldescribed above may also be used. Also, both the range signal and theconverted pattern signal may be used. Also, in the processing at step352 in FIG. 9, the range signal or the converted pattern signal may beused, whichever arrives sooner at the automatic transmission ECU 60.Also, in the processing at step 362 in FIG. 10, the range signal or theconverted pattern signal may be used, whichever arrives later at theautomatic transmission ECU 60.

Also, in the embodiment described above, the range signal is used as thesignal for the processing at step 352 in FIG. 9 and for the processingat step 362 in FIG. 10, but the pattern signal described above may alsobe used. In that case, at step 352, the processing may determine whetheror not the pattern signal detected by the N switch 35 is a specifiedvalue. At step 362, the processing may determine whether or not thepattern signal detected by the N switch 35 is a specified value.

Also, in the embodiment described above, the parking brake engagementprocessing and the parking brake release processing may be executedbased on the detection result of the tensile force sensor 54 in theelectric PKB unit 50. Also, the automatic transmission ECU 60 mayexecute a parking brake engagement processing routine that is shown inFIG. 16, instead of the parking brake engagement processing routine thatis shown in FIG. 9. In this parking brake engagement processing routine,after the automatic transmission ECU 60 operates so as to engage theelectric PKB unit 50 at step 358 (time t21 that is shown in FIG. 17), ifthe tensile force detected by the tensile force sensor 54 becomes equalto or greater than a specified value (time t22) (YES at step 402), theautomatic transmission ECU 60 stops the electric PKB unit 50 (step 404).Next, at time t23, the parking mechanism 27 changes from the releasedstate to the engaged state. Then at time t24, the braking of the wheelbrakes is released.

The automatic transmission ECU 60 may also execute a parking brakerelease processing routine that is shown in FIG. 16, instead of theparking brake release processing routine that is shown in FIG. 10. Inthis parking brake release processing routine, the automatictransmission ECU 60, when the shift range is changed from the P range tothe R range (time t33), the range-switching device 26 operates inconjunction with the change, and the detent lever 31 rotates to an anglethat corresponds to the R range. This causes the parking mechanism 27 tochange from the engaged state to the released state (from ON to OFF)(time t32).

Next, the automatic transmission ECU 60 operates the motor 51 a of theelectric PKB unit 50 such that the parking brakes 53 start operating tochange from the braking state to the released state (from ON to OFF)(time t34) (step 364). Next, when the tensile force detected by thetensile force sensor 54 becomes less than a specified value (time t35)(YES at step 412), the automatic transmission ECU 60 stops the electricPKB unit 50 (step 414).

As is clear from the explanation above, in this embodiment, when theoperator moves the shift lever 61 to the Park range, the parkingmechanism 27 is set to the engaged state by the shift-switching device26, which is mechanically linked to the shift lever 61. Also, when theautomatic transmission ECU 60, which is a control unit, detects that therange position signal has changed to the Park range, the automatictransmission ECU 60 operates the electric PKB unit 50, which is theparking unit, based on the range position signal that indicates the Parkrange. Thus, the parking mechanism 27 can be set to the engaged state,and the parking brakes 53 can apply sufficient braking force, quicklyand reliably, thereby reliably preventing the operator from forgettingto engage the parking brakes 53.

Also, when the operator moves the shift lever 61 out of the Park range,the parking mechanism 27 is set to the released state by theshift-switching device 26, which is mechanically linked to the shiftlever 61. Also, when the automatic transmission ECU 60 detects that therange position signal has changed from the Park range, the automatictransmission ECU 60 operates the electric PKB unit 50 based on the rangeposition signal that indicates a range other than the Park range. Thus,the parking mechanism 27 can be set to the released state, and theparking brakes 53 can be released, quickly and reliably, therebyreliably preventing the operator from forgetting to release the parkingbrakes 53.

The shift ranges include the Park range, the Reverse range, the Neutralrange, and the Drive range. The automatic transmission ECU 60, which isa control unit, operates the electric parking brake unit 50 when therange position signal is a signal to switch the shift range to the Parkrange or a signal to switch the shift range out of the Park range, sothe automatic transmission ECU 60 operates the electric parking brakeunit 50 reliably and correctly according to the shift range.

Also, the range position signals include the range command signal, sothe electric parking brake unit 50, which is the parking unit, can beoperated reliably and correctly according to the operation of the shiftlever.

Also, the range position signals include the range state signal, so theelectric parking brake unit 50, which is the parking unit, can beoperated reliably and correctly according to the actual range state ofthe automatic transmission 20 (the drive unit).

Also, the range command signal is the range signal, which is a detectionsignal for the range that is selected by the shift lever 61, which isthe range selection means, so the electric parking brake unit 50, whichis the parking unit, can be operated with good responsiveness to theoperation of the shift lever.

Also, the range state signal is the signal that is output to theautomatic transmission ECU 60, which is a control unit, from the Nswitch 35, which is the range state detection means that detects theshift range state. Therefore, the electric parking brake unit 50, whichis the parking unit, can be operated reliably and correctly according tothe actual range state.

Also, when the range position signal is the signal to switch the shiftrange to the Park range, the automatic transmission ECU 60 operates theelectric parking brake unit 50, which is the parking unit, to switch theparking brakes 53 to the braking state, thereby reliably preventing theoperator from forgetting to engage the parking brakes 53.

Also, when the range position signal is the signal to switch the shiftrange out of the Park range, the automatic transmission ECU 60 operatesthe electric parking brake unit 50 to switch the parking brakes 53 tothe released state, thereby reliably preventing the operator fromforgetting to release the parking brakes 53.

Also, the range position signals are made up of the range command signaland the range state signal, and the electric parking brake unit 50 isoperated according to either the range command signal or the range statesignal, so the electric parking brake unit 50 can be operated reliably.

Also, the range position signals are made up of the range command signaland the range state signal, and the electric parking brake unit 50 setsthe parking brakes 53 to the braking state according to either the rangecommand signal or the range state signal, while according to the othersignal, the parking brakes 53 are set to the released state, so theparking brakes 53 can be engaged and released reliably.

Also, the parking brakes 53 are set to the braking state before theparking mechanism 27 is set to the engaged state. Thus, when theoperator parks the vehicle, the parking mechanism 27 is set to theengaged state based on a circumstance in which the vehicle is in aparked state, with the wheels held stationary and the like, and there isno movement in the output shaft 24 of the automatic transmission (thedrive unit). Therefore, the generation of loud noise and shock resultingfrom the engagement of the parking mechanism 27 while the output shaft24 is rotating can reliably be prevented.

Also, the parking brakes 53 are set to the released state at or afterthe time when the parking mechanism 27 is set to the released state.Thus, when the operator releases the vehicle from the parked state, theparking mechanism 27 is set to the released state based on acircumstance in which the vehicle is parked, with the wheels heldstationary and the like, and there is no movement in the output shaft 24of the automatic transmission (the drive unit). Therefore, thegeneration of loud noise and shock resulting from the release of theparking mechanism 27 while the output shaft 24 is rotating can reliablybe prevented.

Also, the parking unit may be structured from at least one of theelectric parking brake unit 50, which is the parking brake unit thatoperates the parking brakes 53, and the hydraulic brake unit 70, whichis the wheel brake unit that operates the wheel brakes. Either theparking brake unit or the wheel brake unit is set to the braking statebefore the parking mechanism 27 is set to the engaged state,. Thus, whenthe operator parks the vehicle, it is possible to engage the parkingbrakes after the wheel brakes are engaged and to set the parkingmechanism to the engaged state after the output shaft of the automatictransmission (the drive unit) stops moving, while ensuring a high degreeof freedom in design.

Also, the parking unit may be structured from at least one of theelectric parking brake unit 50, which is the parking brake unit thatoperates the parking brakes 53, and the hydraulic brake unit 70, whichis the wheel brake unit that operates the wheel brakes. Either theparking brake unit or the wheel brake unit is set to the released stateat or after the time when the parking mechanism is set to the releasedstate. Thus, when the operator releases the vehicle from the parkedstate, it is possible to release the wheel brakes after the parkingbrakes are released and to release the vehicle from the parked stateafter the parking mechanism is set to the released state, while ensuringa high degree of freedom in design.

Note that in the embodiment described above, the electric PKB unit 50 iscontrolled by the automatic transmission ECU 60, but a control unit thatexclusively controls the electric PKB unit 50 may also be provided, andthe electric PKB unit 50 may be controlled by that control unit.

Also, in the embodiment described above, the parking brakes of theelectric PKB unit 50 are wheel types that are provided on the wheels,but the parking brakes may be center types in which braking is appliedby drum brakes or the like on the propeller shaft.

Note that the embodiment described above was explained using an exampleof a vehicle equipped with an automatic transmission, but a vehicleequipped with a drive unit that is not an automatic transmission mayalso be used. For example, a hybrid vehicle or the like without anautomatic transmission falls into this category. In the case of a hybridvehicle, the range selection means, such as the shift lever or the likethat is operated by the operator, can select the P range, the R range,the N range, the D range, and the like in the conventional manner.However, in the parking mechanism that is provided in the drive unit,the detent lever that is used is set such that, in the P range, theparking mechanism that is provided in the drive unit engages, in thesame manner as with the automatic transmission, but in the R range, theN range, and the D range, the parking mechanism releases, unlike withthe automatic transmission. Although this case is different from theautomatic transmission case on this point, the detent lever still hasthe role of switching the parking mechanism to the engaged state and thereleased state. Therefore, even in this case, the control flow that isexplained in the embodiment described above can be used, and the anglesignal, which is the range state signal, instead of indicating theposition of the manual valve, indicates whether the detent lever, whichswitches the parking mechanism to the engaged state and the releasedstate, is in the P range or is in the R range, the N range, or the Drange. Moreover, in the case of a hybrid or the like, there are timeswhen the drive unit itself is not set to the Park range, the Reverserange, the Neutral range, the Drive range, or the like, but at thosetimes, the control unit that controls the drive unit operates the driveunit in a manner that is equivalent to the respective ranges. Therefore,even at those times, the embodiment described above can be practiced.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1]

FIG. 1 is a schematic diagram that shows an embodiment of a vehicleparking control system according to the present invention.

[FIG. 2]

FIG. 2 is a schematic diagram that shows the structure of an automatictransmission shown in FIG. 1.

[FIG. 3]

FIG. 3 is an oblique view that shows a parking mechanism shown in FIG.2.

[FIG. 4]

FIG. 4 is a schematic diagram that shows the structure of an automatictransmission ECU shown in FIG. 1.

[FIG. 5]

FIG. 5 is a drawing that explains range position signals.

[FIG. 6]

FIG. 6 is a flowchart of an initialization processing routine that isexecuted by an engine ECU shown in FIG. 1.

[FIG. 7]

FIG. 7 is a flowchart of an initialization processing routine that isexecuted by the automatic transmission ECU shown in FIG. 1.

[FIG. 8]

FIG. 8 is a flowchart of an actual range position change control routinethat is executed by the automatic transmission ECU shown in FIG. 1.

[FIG. 9]

FIG. 9 is a flowchart of a parking brake engagement processing routinethat is executed by the automatic transmission ECU shown in FIG. 1.

[FIG. 10]

FIG. 10 is a flowchart of a parking brake release processing routinethat is executed by the automatic transmission ECU shown in FIG. 1.

[FIG. 1]

FIG. 11 is a flowchart of a termination processing routine that isexecuted by the engine ECU shown in FIG. 1.

[FIG. 12]

FIG. 12 is a flowchart of a termination processing routine that isexecuted by the automatic transmission ECU shown in FIG. 1.

[FIG. 13]

FIG. 13 is a time chart that shows an engagement operation of thevehicle parking control system.

[FIG. 14]

FIG. 14 is a time chart that shows an engagement release operation ofthe vehicle parking control system.

[FIG. 15]

FIG. 15 is a flowchart of another parking brake engagement processingroutine that is executed by the automatic transmission ECU shown in FIG.1.

[FIG. 16]

FIG. 16 is a flowchart of another parking brake release processingroutine that is executed by the automatic transmission ECU shown in FIG.1.

[FIG. 17]

FIG. 17 is a time chart that shows another engagement operation of thevehicle parking control system.

[FIG. 18]

FIG. 18 is a time chart that shows another engagement release operationof the vehicle parking control system.

DESCRIPTION OF THE REFERENCE NUMERALS

-   20 . . . AUTOMATIC TRANSMISSION (DRIVE UNIT)-   26 . . . SHIFT-BY-WIRE APPARATUS-   27 . . . PARKING MECHANISM-   50 . . . ELECTRIC PARKING BRAKE UNIT (PARKING UNIT)-   53 . . . PARKING BRAKES-   61 . . . SHIFT LEVER (RANGE SELECTION MEANS)-   61 a . . . SELECTOR SWITCH (RANGE DETECTION MEANS)-   35 . . . N SWITCH (RANGE STATE DETECTION MEANS)-   60 . . . AUTOMATIC TRANSMISSION ECU (CONTROL UNIT)

1. A vehicle parking control system, comprising: range selection meansthat is operated by an operator and that selects a shift range of adrive unit for a desired range; a range-switching device that operatesin conjunction with the range selection means and that switches aparking mechanism that is provided in the drive unit to an engaged stateand a released state; a parking unit that is operated based on anelectric range position signal, which corresponds to the shift range,and that switches a brake unit that is provided in the vehicle to abraking state and a released state; and a control unit that operates theparking unit based on the range position signal of vehicle.
 2. A vehicleparking control system, comprising: range selection means that isoperated by an operator and that selects a shift range of an automatictransmission for a desired range; a range-switching device that operatesin conjunction with the range selection means and that switches aparking mechanism that is provided in the automatic transmission to anengaged state and a released state; a parking unit that is operatedbased on an electric range position signal, which corresponds to theshift range, and that switches a brake unit that is provided in thevehicle to a braking state and a released state; and a control unit thatoperates the parking unit based on the range position signal of vehicle.3. The vehicle parking control system according to claim 1 or 2, whereinthe shift range includes a Park range, a Reverse range, a Neutral range,and a Drive range; and the control unit operates the parking unit whenthe range position signal is one of a signal to switch the shift rangeto the Park range and a signal to switch the shift range out of the Parkrange.
 4. The vehicle parking control system according to any one ofclaims 1 through 3, wherein the range position signal is a range commandsignal.
 5. The vehicle parking control system according to any one ofclaims 1 through 3, wherein the range position signal is a range statesignal.
 6. The vehicle parking control system according to claim 4,wherein the range selection means has a function that detects theselected range and outputs a range signal, which is a detection signal,to the control unit; and the range command signal is the range signal.7. The vehicle parking control system according to claim 5, wherein therange state signal is a signal that is output to the control unit fromrange state detection means that detects the shift range state.
 8. Thevehicle parking control system according to any one of claims 1 through3, wherein when the range position signal is the signal to switch theshift range to the Park range, the control unit operates the parkingunit to switch the brake unit to the braking state.
 9. The vehicleparking control system according to any one of claims 1 through 3,wherein when the range position signal is the signal to switch the shiftrange out of the Park range, the control unit operates the parking unitto switch the brake unit to the released state.
 10. The vehicle parkingcontrol system according to any one of claims 1 through 3, wherein therange position signal is made up of a range command signal and a rangestate signal; and the parking unit is operated according to one of therange command signal and the range state signal.
 11. The vehicle parkingcontrol system according to any one of claims 1 through 3, wherein therange position signal is made up of a range command signal and a rangestate signal; the parking unit sets the brake unit to the braking state,according to one of the range command signal and the range state signal;and the parking unit sets the brake unit to the released state,according to the other of the range command signal and the range statesignal.
 12. The vehicle parking control system according to claim 8,wherein the brake unit is set to the braking state before the parkingmechanism is set to the engaged state.
 13. The vehicle parking controlsystem according to claim 9, wherein the brake unit is set to thereleased state at one of the time when the parking mechanism is set tothe released state and a time after the time when the parking mechanismis set to the released state.
 14. The vehicle parking control systemaccording to claim 8, wherein the parking unit is structured from atleast one of a parking brake unit that operates a parking brake and awheel brake unit that operates a wheel brake; and one of the parkingbrake unit and the wheel brake unit is set to the braking state beforethe parking mechanism is set to the engaged state.
 15. The vehicleparking control system according to claim 9, wherein the parking unit isstructured from at least one of a parking brake unit that operates aparking brake and a wheel brake unit that operates a wheel brake; andone of the parking brake unit and the wheel brake unit is set to thereleased state at one of the time when the parking mechanism is set tothe released state and a time after the time when the parking mechanismis set to the released state.